Method of securing sheets of dissimilar metals together



Dec. 25, 1956 K. E. WEISS 2,775,030

METHOD OF SECURING SHEETS OF DISSIMILAR METALS TOGETHER Filed May 26, 1954 b Q4 1/ 54 I 8 ya /0"; 6 'g/ 42,534 a i 6146:? e/ K e8 30 a4 Kiley-4. a 3gb qa ee I a I 122131222302 Kafll 1 7. Weziss, by Mm flfijoflnqy Unite tte METHOD OF SECURING SHEETS F DHSSHVHLAR METALS TOGETHER Karl E. Weiss, Arlington, Mass, assignor to New England Lead Burning C0rp., St. Louis, Mo., a corporation of Missouri Application May 26, 1954, Serial No. 432,471 11 Claims. (Cl. 29530) This invention is concerned with a new and novel method of securing together two sheets of dissimilar metals. The invention is particularly concerned with the method of securing a sheet of lead to a sheet of steel, but the invention is equally applicable to securing other types of metallic sheets together provided one of'the sheets has a relatively low melting temperature so that it can readily be melted by a torch.

This invention finds particular use in the manufacture of equipment used in the chemical field, particularly lead lined tanks. In certain chemical processes, closed cylindrical lead lined tanks are used. In such cases it is obvious that in addition to lining the exterior steel tank with lead, the lead lining must also be secured or bonded to the steel interior for otherwise the very weight of the lead combined with negative tank pressures might cause the lead lining to pull away from the outer steel supporting wall.

Various methods of securing a lead lining to steel tanks have heretofore been practiced, such as for example, the bonding of the lead sheet to the steel by tinning or soldering, the use at bolts or rivets which extend through the steel and lead sheet and in which the interior exposed heads are subsequently covered by additional layers of lead or the use of expanded metal lath which is first Welded or bolted to the steel sheet to be filled in subsequently with molten lead to a depth to cover the era-- panded metal lath to the thickness required. All of these previous methods have proved to be slow and time consuming procedures resulting in very high costs per square foot.

The method of the present invention results in a final product in which the steel sheet has spot welded or otherwise atlrxed thereto a layer of expanded metal lath or metal grating and the lead in turn is secured to the metal lath or grating in a manner which holds the lead sheet firmly against the surface of the steel sheet. The method herein disclosed and claimed enables a sheet of lead to'be affixed to a sheet of steel with all the security needed to meet any commercial requirement faster and cheaper than other known processes and is believed to constitute a material advance in this art. The final product resulting from the practice of my method will be somewhat similar to the construction shown in the patent to Zeitler, No. 1,254,558 of January 22, 1918.

While the present disclosure is made with particular respect to attaching a sheet of lead to a sheet of steel, it will be understood that another metal or a metallic alloy might be substituted for the lead sheet provided the other metal or metallic alloy has a melting point low enough to enable it to be melted readily by the use of a torch so that the interstices of the expanded metal lath or the equivalent grating may be readily filled by melting in additional quantities of the metal and the molten metal is capable of fusing itself to a sheet of the same substance. Thus, the invention might be practiced with lead, the preferred material which melts at 621 F., with zinc which melts at 789 F., with tin which Patented Dec. 25, 1956 melts at 450 F., or with alloys of the same or other metals which melt at comparable low temperatures.

When the term lath or grating is used herein, it contemplates a sheet of material having interstices and adapted to be secured to a supporting sheet and capable of receiving molten metal in the interstices to be secured to the lath by physical engagement therewith.

The invention will be more clearly understood as the description proceeds with the aid of the accompanying drawing in which Fig l is a plan view of a sheet of lead showing a piece of expanded metal lath resting thereon.

Fig. 2 shows the first step in the process in which molten lead has been run into the interstices of the expanded metal lath.

Fig. 3 shows the product produced in Fig. 2 in inverted position and resting on a sheet of steel to which it is .to be attached by spot welding the expanded metal lath to the steel at certain locations.

Fig. 4 shows the final product after the practice of the last step of the method in which the lath is secured to the steel, the lead sheet is secured to the lath and the hOles in the lead sheet have been filled in.

The method is practiced in the following manner:

A sheet of lead 2, shown in fragmentary section and being typical dimensions 7%" thick, 8 wide by 36' or 48 long is placed horizontally on any suitable supporting surface. A plurality of holes 4a, 4b, 4c, 4d, etc. conveniently spaced are drilled or otherwise formed through the lead sheet over its entire area. These holes may be made according to any suitable spacing as, for example, six, eight, ten or twelve inch centers and each hole may be in the order of A" in diameter. With the lead sheet thus properly perforated, a piece of expanded metal lath 6 of the same lateral dimensions as the lead sheet is placed thereon. Preferably the expanded metal lath has been rolled flat so that each part thereof in crosssection will appear approximately as shown in Figs. 2, 3 and 4. Thus, formation gives undercut area which help to bind the lead that will be subsequently melted and flowed therein.

With the lath 6 in position on top of the lead sheet 2 as shown in Fig. 2, a workman using a torch and a bar of lead flows molten lead into all of the diamond shaped spaces of the lath as at 8, 10, 12, and 14, but taking particular care not to flow molten lead into the holes 40, 4b, etc. of the sheet 2. The molten lead as it is flowed into the various interstices of the lath, fuses to the sheet 2, flows in under the sides of each part of the lath and is added in such quantity that it will be substantially flush as at 16 with the top surfaces of the lath indicated at 18 and 20. I V

It will be observed that the holes 4a, 41;, etc. are large enough so that regardless of the particular position of the lath 6 on top of sheet 2, a portion of the lath will always extend over each of the holes 4. Thus, in Fig. 1 that portion 22 of the lath extends over hole 4 a and that portion 24 of the lath extends over hole 41). Similarly, as shown in Figs. 2, 3 and 4, lath portion 26 extends over hole 4d.

When the step disclosed in Fig. 2 has been completed, the combined lead sheet and lath are then lifted and placed in inverted position on top of a steel sheet to which the lead sheet is to be atfixed. Such steel sheet is shown at 28 in Figs. 3 and 4. The lath side of the combined lead and lath sheet will now be resting against steel sheet 28 with certain portions of the lath such as 24 and 26 visible through the holes 4b and M. A workman then proceeds with suitable welding equipment to go from hole to hole over the entire area of the lead sheet welding visible portions of the lath to the underlying steel sheet. Thus, the visible portion 24 is welded at 30 to steel sheet 28 and the visible portion 26 is welded as at 32. In this way the lath is securely afiixed to the steel sheet wherever it passes under one of the original holes 4a, 4b, etc.

As soon as the welding of the lath to the steel sheet has been completed, the workman fills up the holes 4a, 4b, etc. by melting lead therein as at 34 and 36 in Fig. 4. In this way all of the holes 4 are filled in with the lead fusing to the surrounding lead portions and covering the previously exposed portions of the lath. After the holes are filled, the surface is smoothed off by use of the torch or a suitable tool.

With the lead sheet 2 aflixed to the steel sheet 28 in this manner, it is then possible to fabricate the combined sheet into any desired form. That is to say, the sheet can be rolled into a cylinder to form a tank Without fear of the lead separating from the surface or the sheet can be cut up and used to provide the fiat surfaces of the tank or any other article.

Experiments have shown that a tank lined according to the foregoing process, can be used with high negative pressures without danger of the lead lining separating from the surrounding supporting shell.

It will also be understood that while the fusible metal sheet is ordinarily secured to a steel supporting surface, other supporting materials could be used in place of steel if they should be found desirable or necessary.

It is my intention to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

I claim:

1. The method of attaching a sheet of fusible metal which melts at a relatively low temperature to a sheet of steel, which method comprises the steps of forming a plurality of holes at spaced intervals in a sheet of the said fusible metal, placing a layer of expanded metal l-ath over said fusible sheet so that solid portions of said lath are in line with the holes in said fusible sheet, flowing additional quantities of said fusible metal into the interstices of the said expanded metal lath and building the fusible metal sheet up to a thickness to include therein the said metal lath, placing the combined sheet of fusible metal and metal lath against a sheet of steel with the lath side of said combined sheet facing said steel sheet, directly securing the metal lath to the sheet steel at those places where solid portions of the lath are in line with and visible through the holes in said fusible metal sheet and then filling in all of the holes with additional fusible metal to give an impervious sheet of fusible metal secured to said metal lath and said metal lath secured to said steel sheet.

2. The method set forth in claim 1 in which said sheet of fusible metal is lead.

3. The method set forth in claim 1 in which said fusible metal is lead and said met-a1 lath is secured to said steel sheet by welding.

4. The method set forth in claim 1 in which the fusible metal flowed into the interstices of said metal lath is built up to a thickness substantially equal to the vertical dimension of said metal lath.

5. The method set forth in claim 1 in which the holes in said fusible metal sheet are large enough to permit the welding of said lath to said steel sheet.

6. The method of securing a sheet of lead to a sheet of steel, comprising the steps of perforating the lead sheet with a plurality of holes of substantial size, securing a sheet of expanded metal lath to the upper surface of said lead sheet by melting additional lead into the interstices of said expanded metal lath to a depth approximately equal to the depth of said lath, placing the combined lead sheet and lath on a sheet of steel with the lath side against the steel, directly fastening the lath to the sheet of steel at those positions where the lath is visible and accessible through the said holes and then filling in the holes with molten lead to provide an impervious continuous lead surface secured to the lath which is in turn secured to the sheet steel.

7. The method set forth in claim 6 in which said lath is fastened to said sheet of steel by Welding.

8. The method of attaching sheets of dissimilar metallic materials to each other comprising placing a fiat grating of a first metallic material on a sheet of a second metallic material having a plurality of perforations in predetermined spaced relation whereby each of said perforations is in communicating alignment with certain solid portions of said grating, filling with said second material the open spaces of said grating that are in communicating alignment with the unperforated portion of said sheet to form a combined sheet, placing an unperforated sheet of said first material in contact with the grating side of the said resulting combined sheet, uniting said certain portions of said grating that are in alignment with said holes with said unperforated sheet, and filling said holes with said second material.

9. The method of claim 8 wherein said first material is steel and said second material is lead.

19. The method of lining a sheet of steel with a sheet of fusible metal comprising the steps of placing a sheet of fusible metal having a plurality of holes in contact with one side of a sheet of metal lath, whereby certain portions of said lath are in visible registration with said holes, filling the interstices of said lath except Where said lath is in registration with said holes with additional quantities of said fusible material to form a combined sheet of fusible metal and lath, placing a sheet of steel against the lath side of the said resulting combined sheet, directly uniting said sheet of steel to said metal lath where the latter is visible through said holes, and filling said holes with additional fusible material whereby said metal lath is entirely embedded in said fusible material.

11. The method of claim 10 wherein said fusible material is lead.

References Cited in the file of this patent UNITED STATES PATENTS 

